Gyratory crusher



S. W. TRAYLOR, -JR

April 24, 1951 GYRATORY CRUSHER 4 Sheets-Shet 1 FIG.v

Filed April 22, 194'? Inventor 5 WILLIAM TRAYLOR, JR.

I Horneys I April 24, 1951 s. w. TRAYLOR, JR

GYRATORY CRUSHER 4 Sheets-Sheet 2 Filed April 22, 1947 Inventor 5. WILLIAM TRAYLOR, JR}

Horneys April 24,1951 5. w; TRAYLOR, JR 2,

- GYRATORY CRUSHER Filed April 22, 1947 4 Shuts-Sheet a m U 9 N FIG. 5.

S.WILLIAM.TRAYLOR, JR.

5. W. TRAYLOR, JR

GYRATORY CRUSHER April 24, 1951 Filed April 22. 1947 4 Sheets-Sheet 4 Patented Apr. 24, 1951 UNITED STATES PATENT OFFICE 9 Claims.

The present invention relates to crushers of the gyratory type, employed in crushing rock, ore, and similar materials. More particularly, the invention relates to new and improved structural features and arrangements of parts adapted to relieve excessive crushing strains, to prevent jamming or breaking of the machinery, and to permit non-crushable objects, such as tramp iron, to pass through the crusher in a new, improved, and more expeditious manner.

A primary object of the invention is to provide a gyratory crusher with yieldable means entirely within the confines of a main casing, permitting displacement of the crushing surfaces when a piece of non-crushable material is encountered. More particularly, the invention aims to provide a construction in which the crushing bowl or concave may be displaced when such material as tramp iron is encountered, thereby to release excessive strains and to permit the material to pass through the apparatus.

Another object of the invention is to provide novel, displaceable backing means for a gymtory crusher bowl or concave and to provide a somewhat resilient seat, to the end that, after the concave has been displaced, it may be returned to its seat without damage to the machine.

Another object of the invention is to incorporate in a gyratory crusher, improved and simplified means for preventing relative rotation between a displaceable concave or bowl and the supporting means or casing therefor.

Another important object of the invention is to provide means for retarding the return to its normal working position of the bowl or concave supporting means, after displacement thereof by a piece of tramp iron or the like. Such retarded return materially facilitates the passage of the non-crushable material between the crushing surfaces, and also prevents a re-seating of the parts with a violent, jarring action, which might damage or fracture certain elements of the machine.

Other and further objects and advantages of the invention will be apparent from a consideration of the following description of certain embodiments thereof, shown for purposes of illustration in the accompanying drawings.

In the drawings,

Figure 1 is a vertical sectional view, with cer tain parts in elevation, of the upper portion of one form of crusher.

Figure 2 is a plan view of a sectional seat for the concave supporting or backing member;

Figure 3 is a vertical section of the seat with the concave supporting or backing member positioned thereon;

Figure 4 is a sectional view and elevational detail of the means for attaching the concave to its backing member;

Figure 5 is a vertical section, partly in elevation of a modification;

Figure 6 is a horizontal section taken substantially on line 6-6 of Figure 5;

Figure '7 is a vertical sectional view on an enlarged scale of a retarding mechanism;

Figure 8 is a transverse section on a still larger scale, on line 8-8 of Figure 7, and

Figure 9 is a perspective View of the valve element shown in Figures '7 and 8.

Referring to Figure l, a crusher is shown comprising a lower frame or casing section I!) having conventional means (not shown) for supporting the lower end of a shaft II, to which gyratory motion is imparted by an eccentric in the wellknown manner. The shaft carries a head l2, which may include a removable mantle, as is understood in the art, having an upwardly facing crushing surface 13. In the type of crusher shown, the upper end [4 of the shaft is unsupported, and may be provided with a conventional cap l5, which may function as a feeder.

The outer circumferential surface of the upper end of the lower casing section [0 is provided with heavy screw threads 16, mating with similar threads ll, formed on the inner circumferential surface of the upper frame or casing section l8.

The latter may be provided with a flange I9 having sockets 20 for the reception of a spanner or other tool to facilitate turning of the upper section on the lower, to raise or lower the former relative to the latter. A threaded ring 2|, having a socketed flange 22 serves'as a lock nut, to maintain the casing sections in the adjusted position.

An outwardly projecting flange 25 at the upper end of frame l8 supports a plurality of arcuate seat elements, each comprising a horizontal flange 26 and an inwardly and upwardly inclined section 27, the outer circumferential corners of the flange 26 being cut away as at 28 to provide a rib 29 (Fig. 3). The end faces 30 of the several arcuate seat elements are spaced apart as indicated in Figures 2 and 3 for purposes hereinafter explained.

The seats jointly serve as a support for a concave-carrying backing member or casting, indicated generally by reference character 33 and comprising a frusto-conical body portion 34, to the undersurface of which the concave 35 is attached; an outwardly extending, integral flange 36, reinforced by radial webs 31, 38; and a downwardly and outwardly inclined flange 39'at the outer end of the flange 36, having an undersurface complemental in form and angle of inclination to the upper, outer surface of the seat portion 21 and adapted to be supported thereon.

The vertically disposed, radial webs 38, here shown as being three in number, are disposed in the slots provided by the spaces between the wardly extending flange 58.

. which may underlie a chute or funnel 4 l, adapted to direct material into the crushing zone between the head and concave.

The frusto-conical body 34 of the backing member 33 has a plurality of apertures 42 formed therein, through which hooks 43, integral with and projecting upwardly from the back surface of the concave may extend. As indicated in Figure 4, each web 31 may be notched to receive a keeper bar 44, over which the hook 43 enggaes. The other end of the keeper bar is bored and threaded, to receive a screw 45, having an end 45 rotatably disposed in an appropriate socket in the body 34 so that, upon rotation of the screw, the bar 44 is lifted, to draw the concave tightly against the undersurface of the backing, the

. 4 an object, with the result that the concave 35 and the backing member 33 tilt upwardly about the diametrically opposite point as a pivot, until the object has worked its way through the crushing zone, whereupon the springs Bl re-seat the backing upon the resilient arcuate seats 2'1.

The form of the invention shown in Figures 5-9 is shown embodied in a gyratory crusher of.

the type in which the upper end of the shaft is mounted in a central hub carried by a spider connected to the side frame or casing, but it parts being maintained in the tightened relation byalug nut All.

The circumferential continuous, horizontally extending flange 25, at the upper end of the upper frame section [8 is provided with an upwardly "jecting rib 54, fitting in the upper notch 28.

The casting 52 further comprises a circumferentially continuous upwardly projecting outer wall 55, connected to the flange 53 by integral webs 55, an inwardly projecting top wall 5? and a down- The undersurface of the top wall 51 is provided with a plurality of cylindrical, downwardly projecting bosses 59, providing circular spring seats 65, to position the upper ends'of downwardly extending coil compression springs 6|, the lower ends of which encircle bosses 62 projecting upwardly from a ring bearing against the upper surface of the concave-carrying backing member 33, at the line of junction between the flanges 36 and 39 thereof.

The spring cage casting 52 is secured in place i by bolts 85 having conical heads 56 disposed in correspondingly shaped bores in the flange 26, extending through the flange 53 and having nuts 6'! on their upper ends. The entire assembly is secured to the upper frame section [8 by bolts 68, extending through aligned bores in thee flanges 53, 26, and 25 and having nuts 69 thereon.

The springs are protected from dust and the like by an inner, sheet metal casing 70, seated i in appropriate notches H in the webs. 31 and disposed in slidable relation with respect to the flange 58 of the spring cage casting.

As is well understood in the art, durin the operation of a crusher of the type with which the present invention is concerned, the cone or head I2 is given a gyratory movement, around the axis X, as indicated by lines Y, with the result that the surface approaches towards and retreats from 3 the working surface of the concave, along a cirthe concave, but such strains are relieved in accordance with the presentinvention, by the yielding of the springs 6| above the position of such nections at the upper ends of the shafts, as shown 7 in Figure 1.

The lower frame or casing section Illa houses the usual eccentric mounting (not shown) for the lower end of the crusher shaft Ila, to which is attached a mantle i2a as is well understood. The upper portion Ida of the shaft is disposed Within a sleeve l5, mounted for rocking movement in a bushing 15, slidably disposed within the hub 11, integral with spider arms 18, carried by an annular top plate casting l9, hereinafter described.

The upper threaded end of the shaft Ila carries a nut 8|, having a spherical lower face 82,

concentric to and mating with a spherical upper face 83 at the upper end of the bushing 16, said end having a spherical undersurface 8Q, seated upon and mating with a spherical surface 85 at the upper 'end of the sleeve '15. All of these spherical surfaces are concentric to the neutral point 86 of thegyratory shaft. The construction provides a dust tight seal for the inner surface of the bushing 16 and the outer surface of sleeve 15, which constitute the Wearing surfaces and withstand crushing strains at the upper end of the shaft. The entire assembly is closed by a removable cap 81.

As in the form previously described, the crusher frame includes an upper section lower section [5a, and the parts may be secured in adjusted position by a locking ring Zia.

The flange 25a at the upper end of the upper frame section supports a plurality of arcuate seats which may be identical to those previously described and include horizontal flanges 26a and upwardly and inwardly inclined flanges 21a.

The backing member 33a for the concave 35a is similar to that previously described, and differs therefrom primarily in that arcuate rail sections 50 are provided at the area of junction between the flange 360. and the seat engaging flange 39a. A plurality of cylindrical bosses 9i are formed on these sections 90,- to 'act as spring centering devices for the lower ends of springs Gla, the upper ends of said spring being positioned by cylindrical bosses 59a, formed integrally on the undersurface of the annular top member 79.

The frusto-conical body portion 34a of the concave-carrying backing member 33a, at three or more equally spaced points in its circumference is'provided with integrally cast upwardly and laterally projecting arms having ball seats 95 adjacent their outer ends. The spring cage casting 52a in this form is generally cylindrical and is provided with a lower flange 55a, arranged as previously described, and an upper, outwardly projecting flange 91 which supports the peripheral portion of the top casting 19. The cylindrical spring cage 52a has a plurality of openings 93,

through which the arms 95 project. The top lBa having. threads Ila, mating with the threads IBa on the.

plate, the spring cage and the arcuate seat members are secured together by bolts 65a having conical lower ends 66a disposed in correspondingly shaped bores and having nuts 61a on their upper, threaded ends. The flanges 53a, 26a, and 25a are secured together by bolts 98a extending through aligned apertures therein and having nuts 69a on their upper ends.

The lower flange 530; of the spring cage casting is thickened, as at I69, at points aligned with the openings 99 and is shaped to provide concave, substantially semi-spherical seats IIII. Interposed between each seat IUI and the seat 96 thereabove, formed in the undersurface of arm 95, is a retarding mechanism indicated generally at I92.

This mechanism comprises a cylinder I93 having a spherical end I94 disposed upon seat I9I and an open end closed by a cap I04 having a central aperture through which a piston rod I05 extends, the joint being made tight by a conventional stufiing box and cap indicated at I06. The upper end of the piston rod is ball shaped, as at I01 and is disposed in the seat 95, while the lower end is enlarged to provide a piston I93, having a plurality of bores I I therethrough, and one or more laterally spaced openings III of restricted size.

Below the piston there is a valve plate H2, closing the ends of the passages III! and having upwardly extending guide fingers H3 integral therewith and disposed in passages Hi], and urged upwardly to closed position by a relatively light spring I14, supported at its lower end by a nut II 5 carried by a bolt Il'o, threaded at its upper end into a bore II? in the lower end face of the piston. The piston I08, piston rod I95, and ball head I9! are urged upwardly by a relatively strong coil compression spring H8, bearing at its lower end against the bottom end face of the cylinder and at its upper end against the piston, in the space between the valve I I2 and the cylinder wall. The cylinder is filled with a liquid, such as oil, as is well understood in connection with many dashpot constructions.

In the operation of this form of the invention,

excessive crushing strains are relieved by the upward movement of the concave 35a, and the backing casting 3311, against the force of springs 6Ia. This lifting or tilting action serves to raise one or more of the arms 95. The compression springs I I8 in the retarding mechanism I92 force the piston I63 and the piston rod upwardly so that the ball head It! follows the movement of the arm 95. This upward movement is substantially unrestricted, since the oil above, the piston is free to flow through the passages IIil, past the valve II2, to the space below the piston.

As the head I2a moves away from the upwardly tilted side of the concave 35a, the concave, un-

der the influence of the springs 6Ia cannot immediately return to its seated position, since the arm 95 is held upwardly by the retarding mechanism I92, in which the flow of oil from the space below the piston to the space thereabove is restricted by the valve II2, automatically closing the passages Ill] and forcing the oil to flow through the restricted passage or passages III, or to leak past the circumference of the piston.

The retarding devices not only prevent a violent, jarring return of the concave backing to its seat, but also produce a new and improved mode of operation and make it possible for the crusher to pass larger bodies of non-crushable material,

such as tramp iron, than would otherwise be pos- ,form of three arcuate sections.

'6 sible, and by using an eccentric throw in the crusher head of smaller extent.

When complicated and expensive feeding mechanisms for crushers are not used, the only way to prevent choking of the crusher and the consumption of excessive power is to employ a relatively small eccentric throw of the head. For instance, experience has shown that, for a setting on the closed side of the crusher, a throw can be used, if the head and concave are of the non-choking type, as shown in the accompanying drawings, but larger throws tend to choke the crusher and take excessive power. With a crusher constructed in accordance with the prior art, with a A closed setting and a eccentric throw of the head, the largest piece of tramp iron that could be discharged would be one having a thickness of 1 In accordance with the present invention, however, much largerpieces may be passed. The backing 36a for the concave 35a may tilt upwardly approximately three inches or more. Since the normal space between the concave and the head, on the open side, in the example under consideration, is 1 it will be seen that the opening, in accordance with the present invention may be a maximum of 4 If the return motion of the concave is retarded, as explained above, the concave Will lag behind the head and provide an abnormally large opening. Hence, with a head gyrating rapidly, such as 300 cycles per minute, the piece of tramp iron or the like will work downwardly a short distance during each cycle and will be discharged far more quickly than if the concave were permitted to follow the gyrations of the head by unrestricted upward and downward tilting movement.

1 As pointed out above, the normal operating clearance between the head and concave may be adjusted, by rotating the upper casing section I8a relative to the lower frame Ifia, thus screwing the upper section and the parts carried thereby, upwardly or downwardly with respect to the lower section and the head, supported in vertically fixed relation with respect thereto.

This adjustment may be eifected by power means in a manner similar to that described in my application Serial No. 696,879, filed September 13, 1946, now Patent No. 2,510,437, granted June 6, 1950. A gear arrangement of the type there described may be mounted within the spider for turning the top part of the frame or casing relative to the lower part. All that is necessary is to provide releasable means for preventing relative rotation between the shaft and spider, in which case the shaft, as it revolves while crushing will turn the whole top shell, thereby providing power adjustment of the crusher.

As a further modification, the arcuate seats for the concave backing may be cast integral wtih the flange 53a of the upper casing section or spring cage 52a, instead of making them in the In the modified construction, the inner edges of the arcuate seating flanges should be disposed on a circle of sufficiently large diameter to clear the inner lower edge of the concave backing, and the flanges 36a and 39a correspondingly enlarged to cooperate with the seat sections. Such an integral construction makes it possible to eliminate the long bolts a, as the combined cage and seat may be simply bolted to the casing section I8a by the short bolts 68a.

It should be understood that the invention is not limited to the details of construction and arrangement of parts shown in the accompanying drawings and described above, but includes all modifications coming within the scope of the appended claims and their equivalents.

I claim:

1. A gyratory crusher comprising a substantially circular frame, a concave, a backing for the concave to which the concave is attached, and means for supporting the backing on the frame, said means comprising a plurality of inwardly projecting, circularly aligned, arcuate seats having their upper faces disposed on an upwardly and inwardly inclined frusto conical surface and their ends spaced apart to provide slots therebetween, a laterally projecting flange associated with the backing disposed on said arcuate seats and having its undersurface disposed on a Irustc conical surface to mate with the upper faces of the seats, a plurality of integral vertical webs on the backing disposed in said slots, and resilient means for urging the flanges downwardly upon the seats.

2.-A crusher comprising a substantially circular frame, a concave within the frame disposed on an upright axis, an upright gyratory crushing head disposed in cooperative relation to the concave to advance toward and retreat from all points on the circumference of the con.- cave in a repeating gyratory cycle, and means for supporting the concave within the frame, said me'ans comprising an annular backing member to which the concave is attached, having a plurality of arms pro ecting laterally into alignment with said frame a circumferentially extending seat surface carried by the frame receiving the backing member, a plurality of springs urging the backing member downwardly, and a plurality of dashpot assemblies interposed between said arms and the frame, said concave and backing member being tiltable upwardly at 1 .all points around the circumference of the concave against the force of said springs to relieve excessive crushing pressures during advance of the head upon encounter with an uncrushable object, and being restrained in their return movement under the influence of the springs by said independent dashpot assemblies, as the head retreats from the concave, thereby increasing the space between the head and concave to facilitate the passage therebetween of suchlan uncrushable object.

3. A crusher comprising a substantially circular frame, a concave within the frame disposed on an upright axis, an upright gyratory crushing head disposed in cooperative relation to the concave to advance toward and retreat from all points on the circumference of the concave in a repeating gyratory cycle, and means for supporting the concave within the frame, said means comprising an annular backing member to which he concave is attached, said backing having a downwardly and inwardly facing, circumferentially extending surface, a plurality of upwardly facing spring seats above said surface and a plurality of laterally projecting arms, a circumferentially extending inwardly and upwardly projecting seat surface carried by the frame receiving said'surfaces of the backing member, spring cage means carried by the frame, a plurality of springs therein seated upon the spring seats and urging the backing member downwardly, and a plurality of dashpot assemblies interposed between said arms and the frame, said concave and backing member being tiltable upwardly against the force of said springs to relieve excessive crushing pressures, and being restrained in their return movement under the innuence of the springs by said dashpot assemblies, whereby the concave is restrained against following the head in the retreating portion of its gyratory cycle, thereby materially increasing the space between the head and concave to facilitate the passage therebetween of an uncrushable object.

4. A crusher comprising a circular frame, a concave disposed therein on an upright axis, an upright gyratory shaft and a head carried thereby for advancing and retreating movement toward and from all points on the circumference of the concave in a repeating gyratory cycle, and means for-supporting the concave in the frame, said means comprising an annular backing member to which the concave is attached, having arcuate downwardly facing surfaces, a plurality of circumferentially spaced substantially vertically disposed webs at the ends of said surfaces, and a plurality of upwardly and laterally projectlng arms; a plurality of arcuate seating surfaces carried by the frame upon which said surfaces of the backing member are disposed, the ends of the seating surfaces being spaced apart to provide slots for the reception of said webs to prevent relative rotation between the backing and the frame, a plurality of coil compression springs interposed between the frame and the backing member and urglng the latter downwardly upon said seating surfaces and a plurality of independent dashpot assemblies interposed between said arms and the frame, whereby the concave may be displaced upwardly at any point during the advancing portion of the cycle by encounter with an uncrushable object and whereby the concave is restrained against following the head in the retreating portion of its cycle and the crushing space is thereby increased to facilitate passage of such uncrushableobject.

5. A crusher comprising a circular frame, a concave disposed therein on an upright axis, an upright gyratory shaft and a head carried thereby for cooperation with said concave, a spider supported by the frame and including a central hub having a bore in which the upper end of said shaft extends and an annular peripheral flange having a series of downwardly facing spring seats; and means for supporting the concave in the frame, said means comprising an annular backing member to which the concave is attached, having arcuate downwardly facing surfaces, a plurality of circumferentially spaced substantially vertically disposed webs and a plurality of equally, circumferentially spaced upwardly and laterally projecting arms; a plurality of arcuate seating surfaces carried by the frame upon which said surfaces of the backing member are disposed, the ends of the seating surfaces being spaced apart to provide slots for the reception of said webs to prevent relative rotation between the backing and the frame, a plurality .of coil compression springs interposed between said spring seats and the backing member and urging the latter downwardly upon said seating surfaces and a plurality of independent dashpot assemblies interposed between said arms and the frame.

6. A crusher comprising a circular frame, a concave disposed therein on an upright axis, an upright gyratory shaft and a head carried thereby for cooperation with said concave, a spider supported by the frame and including a central hub having a bore in which the upper end of said shaft extends and an annular peripheral flange having a series of downwardly facing spring seats; and means for supporting the concave in the frame, said means comprising an annular backing member to which the concave is attached, having arcuate downwardly facing surfaces, a plurality of circumferentially spaced substantially vertically disposed webs and a plurality of equally, circumferentially spaced upwardly and laterally projecting arms; a plurality of arcuate seating surfaces carried by the frame upon which said surfaces of the backing member are disposed, the ends of the seating surfaces being spaced apart to provide slots for the reception of said webs to prevent relative rotation between the backing and the frame, a plurality of coil compression springs interposed between said spring seats and the backing member and urging the latter downwardly upon said seating surfaces and a plurality of independent dashpot assemblies interposed between said arms and the frame, each dashpot assembly comprising a cylinder and piston assembly substantially freely movable to extended position in an upward direction, a spring urging the parts in that direction to freely follow upward movement of said arms and a valve restraining contracting movement of the piston and cylinder upon downward movement of said arms.

'7. A crusher comprising a circular frame, having a plurality of circumferentially spaced openings adjacent its upper end, a concave disposed therein on an upright axis, an upright gyratory shaft and a head carried thereby for cooperation with said concave, and means for supporting the concave in the frame, said means comprising an annular backing member to which the concave is attached, said member comprising a downwardly facing surface and a plurality of equally, circumferentially spaced arms projecting laterally through said openings in the frame; a seating surface carried by the frame upon which said surface of the backing member is disposed, a plurality of springs interposed between the frame and the backing member and urging the latter downwardly upon said seating surface and a plurality of independent dashpot assemblies interposed between said arms and the frame and positioned exteriorly of the frame, to restrain the return movement of the backing member to the seating surface under the influence of said springs, after displacement of the concave and backing member by the passage through the crusher of non-crushable material.

8. A crusher comprising a circular frame having a plurality of circumferentially spaced openings adjacent its upper end and a plurality of dashpot seats projecting from the exterior surface thereof vertically aligned with said openings, a concave disposed in the frame, a gyratory shaft and a head carried thereby for cooperation with said concave, a spider supported by the frame having a central hub embracing the upper end of the shaft and an annular peripheral flange secured to the frame and having a series of downwardly facing spring seats disposed interiorly of the frame; and means for supporting the concave in the frame, said means comprising an annular backing member to which the concave is attached, having downwardly facing surfaces, a plurality of upwardly facing spring seats aligned with the first mentioned spring seats, and a plurality of arms projecting through said openings in the frame and having downwardly facing dashpot seats adjacent their ends aligned with the first mentioned dashpot seat; a plurality of arcuate seating surfaces carried by the frame upon which said surfaces of the backing memher are disposed, a plurality of coil compression springs inside of the frame, interposed between said spring seats and urging the backing member downwardly upon said seating surfaces, and a plurality of dashpot assemblies disposed exteriorly of the frame and interposed between the dashpot seats associated with the frame and said arms, respectively.

9. A crusher comprising a circular frame having a plurality of circumferentially spaced openings adjacent its upper end and a plurality of dashpot seats projecting from the exterior surface thereof vertically aligned with said openings, a concave disposed in the frame, a gyratory shaft and a head carried thereby for cooperation with said concave, a spider supported by the frame having a central hub embracing the upper end of the shaft and an annular peripheral flange secured to the frame and having a series of downwardly facing spring seats disposed interiorly of the frame; and means for supporting the concave in the frame, said means comprising an annular backing member to which the concave is attached, having downwardly facing surfaces, .a, plurality of circumferentially spaced, substantially vertically disposed webs, a plurality of upwardly facing spring seats aligned with the first mentioned spring seats, and a plurality of upwardly and laterally extending arms projecting through said openings in the frame and having downwardly facing dashpot seats adjacent their ends aligned with the first mentioned dashpot seat; a plurality of arcuate seating surfaces carried by the frame upon which said surfaces of the backing member are disposed, the ends of the seating surfaces bein spaced apart to provide slots for the reception of said webs to prevent relative rotation between the backing and the frame, a plurality of coil compression springs inside of the frame, interposed between said spring seats and urging the backing member downwardly upon said seating surfaces, and a plurality of dashpot assemblies disposed exteriorly of the frame and interposed between the dashpot seats associated with the frame and said arms, respectively.

SAMUEL W. 'I'RAYLOR, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,953,472 Fahrenwald Apr. 3, 1934 1,961,811 Becker June 5, 1934 2,135,324 Brown Nov. 1, 1938 2,223,956 Gruender Dec. 3, 1940 2,327,384 Annesley Aug. 24, 1943 2,409,391 Rumpel Oct. 14, 1946 FOREIGN PATENTS Number Country Date 873,312 France Mar. 16, 1942 471,842 GreatBritain Sept. 13, 1937 66,645 Norway Sept. 22, 1938 

